Normally-closed switch



A June 9, 1925. 1,541,632

J. EATON NORMALLY CLOSED SWITCH Filed April 12, 1920 m? *"M /0 Pi g1. Fig.2.

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/a y a O O O Fig-3- l6 Inventor;

John Eaton His Attorney,

Patented June 9, 1925.

UNITED STATES PATENT OFFICE.

JOHN EATON, OF SCHENECTADY, NEW YORK, ASSIGNOR T GENERAL ELECTRIC COM- PANY, A CORPORATION OF NEW YORK.

NORMALLY-CLOSED SWITCH.

Application filed April 12, 1920.

To all whom it may (07106;71.

Be it known that I, JorrN EATON, a subject of the King of Great Britain, residing at Schenectady, in the county of Schenectady, State of New York, haveinvented cer tain new and useful Improvements in Normally-Closed Switches, of which the followin is a specification. i

Iy invention relates to switches which are biased to the closed position andv particularly switches which are biased to the closed position b the action of gravity.

One of the o jects of my invention is to provide an improved switch of this character which will not open its contacts in. response to the rebound of the gravity operated means which effects the closing of the switch contacts, or in response to shocks or jolts. Another object of my invention is to provide an improved switch of this character in which the switch cont-acts shall have a wiping action in closing and in the closed position the contacts shall have a spring pressure applied which will maintain the contacts closed.

A further object of my invention is to provide an electromagnet switch of the normally closed type in which the electroi'nagnet which is provided for effecting the open- 30 ing of the switch contacts is used to set up a magnetic flux which will extinguish the are formed between the switch contacts in opening.

For a better understanding of my invention reference is had to the accompanying drawings in which I have illustrated one form of my invention in concrete form for purposes of illustration, and in which Figure 1 is a front view of an electromagnet switch embodying my invention, with the outside cover removed and the switch contacts in the closed position; Fig. 2 is a side view showing certain of the parts in section; Fig. 3 is a fragmentary view of the switch operating mechanism with the switch contacts in open position; and Fig. 4 is a simplified diagram illustrating one of the uses of my invention.

Referring to the drawings, the parts of the switch mechanism are enclosed and supported within a casing 10 of magnetic material. The stationary switch contact 11 is secured to and insulated from the casing 10, and the resiliently mounted movable switch contact 12 is secured to the end of Serial No. 373,062.

the lever 13 which is pivoted to the casing at 14-. The movable contact 12 is secured to the lever 13 by means of the bolt 15 and is insulated from the lever by means of the tubes of insulating material 16. The electromagnet which is provided for opening the switch contacts comprises a winding 17 and a plunger 18, which serves as a movable actuating member for eifecting the opening and closing of the switch contacts. Thelower end of the plunger 18 is slotted as shown in Figs. 2 and 3. A pin 19 which passes through the end of the plunger 18 is adapted to engage the lever 13 so as to move the lever and thereby open the switch contacts when the winding 17 is energized and the plunger drawn upward within the winding. A link 20 pivotally connected to the casing 10 at 21 and also pivotally connected with the plunger 18 at 22 is provided for applying spring pressure to the contacts in closing. The spring 23 connects the lever 13 with the lever or link 20. A post 24 with a screwthread on the end is pivoted for securing the cover of the casing in place.

As thus constructed and arranged, the operation of my invention is as follows: Assume that the various parts are in position as shown in Figs, 1 and 2, that is, that the switch contacts 11 and 12 are closed and that it is desired to open the contacts and deenergize the translating device 25 controlled by the switch. The pilot switch 26 will first be closed, thereby energizing the Q1.

winding 17 of the electromagnet from the source of supply 27. The plunger 18 will at once be drawn upward, but the initial movement of the plunger has no efiect whatsoever on the opening of the switch 0011- 2.7.5;

tacts, since the plunger must travel a certain distance before the pin 19 will engage the lever 13. This is very advantageous, because the plunger 18 has a considerable travel and the pull on the plunger is the 2'24;

least in its lowermost position. The plunger is therefore not required to do any work in opening the contacts until after it The lever or link 227- iii) ill

23, but does not effect the opening switch contacts. lVhen the pin 19 the lever 13, the lever 13 will be rotated clockwise about its pivot A- and the movable contact 12 will first slide upward a small distanre along the stationary contact 11 before it leaves the stationary contact at an angle in response to the further movement of the plunger 18 within the magnet Tinding 1?, the resiliency ot' the support for the contact 12 permitting this contact to first slide upward before breaking engagement with the contact: 11. In the final upper position of the plunger 18 the various parts will be their respec ive positions shown in l t w'll be observed that the con" a. 12 has been moved through a more hit ited range oi movement than the range of moven'ie t of the plunger and that in the upper position the spring 23 has been essed so that the compression 1;; is present to a st the force in closing the switch contacts the winding 17 is deenergized. l t

tact 11 is such a position that it is in the path of the lines of flux set up by the net winding 1'? so that the are formed between the two contacts when the contacts open is extinguished by the flux of the winding.

lVith the switch in open position and the parts in their positions shown in Fig. 3, it the magnet winding is deenergized the plunger 18 will at once drop and the pressure of the spring 23 will assist the force of gravity in the initial downward move ment of the plunger. The lever 13 will be permitted to drop, rotating counter-clockwise about its pivotal support 14-. The movable conta t 12 will be rotated counterclockwise through a limited angular dis tance and will come into engagement with the stationary contact 11 at about the same time that the pin 19 is ready to drop tree of the lever 13. Bit this line the link 20 is ready to apply spring pressure to the (011- tacts throw r th spring The plunger 5:; t). V will drop to its lower position (that shown on F 1), and in the linal movement of the plunger the contact 12 will slide along the stationary contact 11, th reby giving a wiping action to the contacts in closure. The

contacts will be maintained closed by the weight of the plunger 18 acting through the link 20 and the spring In the final position ot' the plunger the spring 23 is compressed so as to apply considerable spring pressure to the contacts, and this spring also rve to cushion the tall ot the plunger. It nil be observed that although the glut is very apt to rebound after it has tallen to its lowest posit-ion, nevertheless the switch contacts will not be in any way affected by the rebound of the plunger, since the plunger will never rebound to the extent that the pin 19 will engage with the lever 13. It will also be observed that by reason of the position of the parts and from the fact that the plunger has moved through a greater range of movement than the range of movement of the contact 12, the plunger acting through the link 2t) will apply cv'msi zlcrable spring pressure to the switch contacts and the contacts will not be jarred open.

It will be apparent from the above description that I have provided an electromagnetically operated normally closed switch in which the rebound oi the plunger of the electromagnet does not effect the opening of the switch rout-acts, also that the switch contacts are given a wiping action in closing and in opening, that consider able spring pressure applied to the switch contacts in the closed position, and that the are set up by the opening of the switch contacts is quickly disrupted by the mag netic flux ot' the operating elcctroniagnet.

hat I claim as new and desire to cure by Letters Patent ot the United States, is

1. A switch of the normally closer l type comprising a rigid switch contact and a cooperating movable contact, an actuating member for the movable contact biased to a position at which the contacts are closed, and connections between the actuating member and the said movable contact whereby the movement of the actuating member to its biased position moves the said contact angularly into engagement with the rigid contact and then gives the contacts a wiping action, the said connections arranged to permit the contacts to be maintained closed during the rebound of the actuating member.

A switch of the normally closed type comprising a pair of relatively movable switch contacts, an actuating member therefor biased to a position at which the cont; s are closed. and connections between the actuating member and one 0'? said contacts whereby the movcmcnt of the actuating member to its bi sed position moves the said contac anguhirly into engagement with the other contact and then increases the pressure between the contacts, the said connections arranged to permit pressure between the contacts to be maintained during the rebound of the actuating member. h

3. A switch of the normally closed type comprising a rigid switch contact and a cooperati movable contact, an actuating member lot too movable coiitact held in a p 'tion at which the contacts are opened i st its bias due to gravity to a position at vnich the contacts are closed, and connections between the actuating member and the said movable contact whereby upon the re ease of the actuating member the sail with tho rigid contact andthen slid along the said rigid contact as pressure is applied between the contacts. I

4. A switch of the normally closed type comprising a stationary rigid switch contact, a movable switch contact,'an act-nab,

ing member therefor operated by gravity to close the contacts, and connections between the actuating member and the movable contact whereby the movable contact is moved angnlarly into engagement with the stationary contact and then given a wiping action with the stationary contact as pressure is applied and maintained to the contacts.

5. A switch of the normally closed type comprising a rigid switch contact and a cooperating switch contact movable through a limited distance into engagement with the said rigid contact, an actuating member for the said movable contact biased to a position at which the contacts are closed, the said actuating member having a greater range of movement than the range of movement of the said movable'switch contact, and connections between the actuating member and the said movable contact whereby the movable contact is moved into engagement with the rigid contact during the initial movement of the actuating member and spring pressure is applied to the contacts as the actuating member completes its movement.

(3. A switch of the normally closed type comprising a stationary switch contact, a movable switch contact, an actuating member therefor operated by gravity to close the contacts, the said actuating member having a predetermined range of movement, and connections between the actuating member and the movable contact whereby the initial movement of the actuating member moves the movable contact through a more limited range of movement and increasing spring pressure is applied to the contacts as the actuating member completes its movement to the one end of its range of movement.

7. A switch of the normally closed type comprising a pair of switch contacts, an actuating member therefor held in a position at which the contacts are opened against its bias due to gravity to a position at which the contacts are closed, and a system of levers connecting the actuating member with one of the switch contacts, whereby upon the release of the actuating member the contacts are closed by the initial movement of the actuating member and the pressure between the contacts is increased by the continuation of the movement of the actuating member.

8. A switch of the normally closed type comprising a stationary switch contact, a

movable switch contact, an actuating member therefor biased to one position at which the contacts are closed and movable against its bias toa second position at which the contacts are opened, a spring interposed between. the actuating member and the movable contact, and connections whereby the spring is put under strain to apply pressure to the contacts in the first position of the actuating member and is put under strain in the second position of the actuating member to assist the bias of the same to the first position.

9. A switch of the normally closed type comprising a pair of switch contacts, an electromagnet having a movable actuating member therefor, the said actuating member biased to a position in which the switch contacts are closed and movable against its bias to open the contacts in response to the energization of the magnet winding, and connections whereby the initial movement of the actuating member to its biased position closes the contacts, the final movement ofi the actuating member applies spring pressure to the contacts, and the contacts are maintained closed during the rebound of the actuating member.

10. A switch of the normally closed type comprising a stationary switch contact, a movable switch contact, an electromagnet having a movable actuating member there'- for, the said actuating member biased to a position in which the switch contacts are closed and movable against its bias to open the contacts in response to the energization of the magnet winding, and means comprising a plurality of cooperating levers connecting the actuating member with the movable switch contact, whereby the contacts are given a wiping action in closing, spring pressure is applied vto the contacts in the closed position, and the contacts are maintained closed during the rebound of the actuating member.

11. A switch of the normally closed type comprising a stationary switch contact, a movable switch contact, an eleotromagnet having a movable actuating member therefor, the said actuating member biased by gravity to a position in which the switch contacts are closed and movable against its bias to open the contacts in response to the energization of the magnet winding, a lever pivoted at one end of a stationary support, l

having the movable contact secured to the other end thereof and acted upon by the actuating member of the electromagnet, a lever having one end pivoted to the actuating member and the other end pivoted to the stationary support, and a resilient connection between the two levers, whereby the contacts are given a wiping action in clos ing, spring pressure is applied to the con tacts in the closed position, and the contacts til) actuated against assist the movement of the actuating member toward its biased position, and a loose :a

connection between the actuating member and the contact-carrying member arranged to permit a predetermined movement of the actuating member away from its biased position after the said contacts are in engagement, whereby a rebound of the actuat ing member will not be transmitted to the contact-carrying member.

In Witness whereof, I have hereunto set my hand this 10th day of April, 1920.

JOHN EATON. 

